Delivery of ionic molecules to anterior chamber by iontophoretic contact lenses

Abstract

Ophthalmic delivery via iontophoresis is currently achieved by placing an electrode on the cornea with a counter electrode on the ear or forehead. Here we test the feasibility of placing both electrodes diametrically opposite on a contact lens to create field gradients to transport ionic drugs into the cornea.Commercial lenses loaded with nile blue and fluorescein as hydrophobic and hydrophilic drug analogs, respectively were placed on cadaver rabbit eyes. Electric field gradients were created by placing cathode and anode on the lens diametrically opposite to each other. The incorporation of an electric field (0.125 m–0.250 mA), showed an increased uptake of nile blue and the quantity was a function of the duration of the electric field and the amount of applied current. Similar increases in flux were observed for fluorescein. Confocal fluorescence imaging also shows increased penetration of the dyes in presence of the field. An equivalent circuit model suggests that the field gradients are much stronger in the direction perpendicular to the cornea, which results is minimal short circuiting of current through the tear film. The incorporation of an electric field into a lens could be a less invasive and more effective approach to achieve ophthalmic drug delivery via iontophoresis.